Common salt, i.e. sodium chloride, is the additive most frequently used in food and beverage preparation both for household and industrial use. It is necessary to consume a certain amount of sodium ions and chloride ions with the food, but the intake of sodium chloride is usually much larger than the minimum required to maintain the salt balance of the body.
To people suffering from certain diseases, such as increased blood pressure, large amounts of NaCl-intake are considered to be injurious. Furthermore, a large intake of sodium ions can displace the balance between sodium and potassium in the body.
Therefore, in order to control the intake of salt, it has been proposed to use various salt combinations, wherein sodium chloride has been partially replaced by other salts, especially potassium chloride.
Replacement of sodium chloride by other chemical compounds pounds entails several disadvantages, inter alia a taste deterioration due to the fact that only sodium chloride can provide the correct salty taste sensation. It is possible to use additives which conceal or disguise this deviation in taste, but only a few additives are acceptable for use in food products. The more the amount of sodium chloride in the salt product is decreased, the greater is the taste deviation problem.
A further problem is that when various pulverulent compounds are intermixed, the mixture will easily become inhomogeneous, especially if it consists of grains of different sizes and densities, which may result in unexpected and unpleasant taste sensations. The problem is particularly distinct when the salt mixture is to be dispensed from a caster. Storing for long periods of time may cause stratification of the product which increases this problem.
WO 86/05954 (Sundien) describes a mineral salt product containing mineral salts in the same relative proportions as in ocean water, apart from a reduced content of sodium chloride. This product contains trace minerals which are considered important for the human health. However, the product has a relatively high content of hygroscopic and bitter magnesium salts.
DE patent publication No. 3,008,171 (Wixforth) discloses a method for the preparation of a salt product by evaporation of water from the Dead Sea. The intermediate salt product obtained contains the K/Mg-double salt carnallite. This intermediate product is, however, unfit for human consumption without the addition of NaCl. The molar ratio of Mg to K is about 7:1 in the Dead Sea, which means that only 1:7 of the magnesium is present as carnallite nallite in the end product. The remaining magnesium will therefore be present as magnesium chloride and/or magnesium sulphate which both are bitter tasting, hygroscopic and present practical problems by storage and use. Furthermore, the NaCl-containing end product is prepared by mere mixing which does not ensure that a homogenous salt product can be obtained.
WO 85/00958 (Rood et al.) discloses a salt product in the form of a mixture comprising 40 to 50% by weight of sodium chloride, 25 to 35% by weight of potassium chloride, and 15 to 25% by weight of magnesium sulphate and/or magnesium chloride. The mixture consists of separate crystals of the same size which should ensure that the mixture is more homogeneous. Rood et al. alleges that by that method, a salt composition is provided which comprises magnesium and potassium salts, has a low NaCl content and has a better taste and a diminished segregation of the different components, when compared with other known low sodium salt mixtures. Even though there might be some improvement with respect to commonly mixed low sodium containing compositions, the salt of Rood does not provide for a fully satisfactory taste, and it is still very hygroscopic due to the presence of hygroscopic magnesium salts. Hence, there still exists a need for further improvement.
Japanese patent application Kokai 84/198953 (Kobayashi Seiyaku K.K.) discloses a salt composition comprising NaCl and KCl mixed with powdered solidified bittern. The concentration of the bittern is in the range of 1-20% by weight based on the total weight of the product. Several preparation methods, including that of dry mixing of the components, are suggested. By another proposal, NaCl, KCl and bittern are dissolved in fresh water and the solution is condensed by a conventional method. As conventional methods, vacuum condensation, kettle condensation and spray drying are mentioned. In case one of these methods is used, the formation of a double salt cannot be excluded in case of very specific conditions. However, such conditions are not disclosed at all, nor is their any hint to the preference of one of these condensation methods. The importance of the double salts was not at all recognized.
WO 90/00522 (Sundstrom) discloses a salt product for use in household and within industry having a reduced content of sodium chloride, which product comprises crystals of sodium chloride and/or potassium chloride adhered to the crystals of kainite and/or carnallite. Not only is it very difficult to produce pure K/Mg-double salt, but the process as described will be very unpractical, due to all the specific measures that has to be taken care of in order to obtain a coating which does not come off by handling of the product. Furthermore, the product obtained is not homogeneous throughout the particle, and will, due to the presence of potassium chloride in the coating, provide a metallic-bitter aftertaste.
It is the object of the present invention to provide a mineral salt product having a low content of sodium chloride, and which is not encumbered with the above problems and disadvantages with segregation, bitter taste, and hygroscopicity, as well as a simple and economic method for the preparation of the mineral salt product.